I Kings 1  David has come to the last years of his life.  He  was physically weak and apparently bedridden.  One of David's sons, Adonijah, decides to take over the position of king, without the knowledge or blessing of his father.  The fact that he does this secretly and behind his father's back, reveals much about his character.  Adonijah took Joab, his father's cousin and former head of David's army and Abiathar, the priest with him to a place called the "stone of Zoheleth"  ( the serpent stone) to offer sacrifices and to proclaim himself as king.  The fact that he offered sacrifices outside of the tabernacle again reveals a defect in Adonijah's character and a lack of faithfulness to the Lord God of Israel.  Adonijah invited most of his brothers to this event.  The list of those not invited is also very telling:
Zadok the priest - unlike Abiathar, who descended from the same line as Eli, Zadok was a descendent of Aaron from the line of Eleazar.  This line of priests would continue, while the prophecy about Eli and the end of their line of high priests comes to a close with Abiathar.
Benaiah and Shimei and Rei - all loyal to David and part of his government in Jerusalem.
Nathan the prophet - a faithful man of God
The mighty men - loyal soldiers that had followed and helped David for many years
And lastly - Solomon - his brother.

David had at least 15 sons, including those of his concubines.  From all of these, Solomon seems to be the only one excluded from Adonijah's coup of the kingdom.  Nathan is the one who breaks this news, coming to Bathsheba first.  Bathsheba realizes the seriousness of this situation, she tells David, "..as soon as my the lord the king sleeps with his fathers, ... I and my son Solomon will be considered offenders".  Unless action was taken by David immediately, Solomon and his mother were doomed.
David had apparently promised to make Solomon king after him.  It was a vow he made "by the Lord God of Israel".  David takes action and Solomon is proclaimed king that very day.  He is anointed by Zadok and Nathan.  He is placed on David's mule and he is seated on David's throne.  When the whole city shouts with joy over this turn of events, those at Adonijah's event turn and run.  Adonijah himself runs to the tabernacle and clings to the altar there.  He wants Solomon to swear not to kill him ( although that had been his intention for Solomon before the turn of events).   Solomon doesn't make any promises, " If he will be a worthy man, not one of his hairs will fall to the ground; but if wickedness is found in him he will die." 

Adonijah is found to be wicked and is killed. We know that Solomon turned out to be a better choice, at least for a while.

The truth we can gain from this passage is this:  God always knows what is in our hearts.  He knows what is found in us - worthiness or wickedness.  His grace is given to us so that we can turn from wickedness to worthiness.  We have so much to be thankful for!

Father, thank you for sending a Redeemer, for giving us forgiveness and making us pure and holy before You.  We cannot stand firm in faith except by Your great compassion upon us.  Fill our hearts with Your love, guide our steps in Your paths, and help us to walk as worthy men and women before You. In Jesus we come. Amen